Tube bending machines having carriages which grasp a tube and position and orient the tube at a bend head are known in the art. Such carriages typically move the tube longitudinally to position the desired segment for bending and also rotate the tube to orient it so that bending will occur in the proper plane.
However, because some tube configurations during bending are such that a particular bend would be prevented since it would require that the forward part of the tube be moved through space occupied by the machine, some bending machines have dual bend heads which permit bending of the tube to take place on either side of the machine. Machines with such dial bend heads have thus required a carriage structure which is capable of orienting a tube along two different axes for bending, one axis for each set of bend components of the dual bend head.
One structure which has been used provides a dual carriage with duplicate parts associated with each of the bend axes. This structure requires duplication of numerous parts and is thus expensive. Another structure which has been used provides a carriage on a track, which track is adapted so that it may be moved to align with either of the axes. Such a structure is shown in U.S. Pat. No. 4,201,073. Changing a carriage on such a track from one axis to the other is difficult and unwieldy. Further, such structures often do not provide parallel bend axes as is desirable.
Still another structure which has been used supports the carriage on one side a central track and the track and carriage are pivoted 180.degree. between bend axes defined on diametrically opposite sides of the track. Such a structure is shown in U.S. Pat. No. 4,313,324. However, such structures when automatically pivoted between axes require costly components for accomplishing the pivoting. Further, pivoting the carriage and track manually is difficult and unwieldy since the operator must lift the carriage and then push it laterally across the top to the other side.
The present invention is directed toward overcoming one or more of the problems as set forth above.